(142j) Mechanical Response of Cancer Cells in Confined Microcapillary Flow

Investigations of confined flow of tumor cells are important for understanding the hydrodynamic mechanisms involved in cancer metastasis. However, very little is known fundamentally about the role of cell mechanics in regulating the flow-induced squeezing of cancer cells through narrow capillaries. To investigate the rheological response of cancer cells during their flow-induced squeezing in a confined microchannel, we measured the excess pressure drop as a function of cell confinement. We conducted additional experiments with passive particles including emulsion droplets, soft elastic particles and poroelastic drops. We find that the excess pressure drop shows no apparent dependence on elastic modulus or droplet interfacial tension, but depends significantly on the drop internal viscosity. The excess pressure drop for cancer cells lies between two bounds determined by the viscous drop and elastic particle limit respectively. Our results suggest that cancer cells flowing through narrow capillaries can be modeled as poroelastic objects, where the hydrodynamic pressure squeezing the cell deforms the cytoskeletal network and causes the infiltrated fluid to be distributed within the cell. The biological implications of our results for cancer metastasis will be discussed.